Various types of films where multiple layers of thermoplastic resin are layered have been proposed and are used, for example, in order to prevent glass from being broken and greatly scattered by pasting a multilayer film having excellent anti-tearing properties to the surface of the glass (Japanese Unexamined Patent Publication H6 (1994)-190995 (page 2), Japanese Unexamined Patent Publication H6 (1994)-190997 (page 2) and Japanese Unexamined Patent Publication H10 (1998)-76620 (page 2)).
In addition, there exist films where multiple resin layers having different indices of refraction are alternately layered, and thereby, a particular wavelength is selectively reflected (Japanese Unexamined Patent Publication H3 (1991)-41401 (page 2), Japanese Unexamined Patent Publication H4 (1992)-29.5804 (page 2) and Japanese Translation of International Unexamined Patent Publication H9 (1997)-506837 (page 2)). From among these, films which selectively reflect a particular wavelength work as a filter for transmitting or reflecting particular light are used as a film for backlight of, for example, a liquid crystal display.